In watches, TV sets et cetera, flat displays using liquid crystal devices are now widely employed and a liquid crystal orientation film is used in the liquid crystal device. The liquid crystal orientation film has hitherto been formed by, for example, the so-called oblique vapor deposition method in which SiO.sub.2, Au or the like is deposited obliquely, or the so-called rubbing method comprising the step of coating a substrate with a polymer film such as a polyimide type resin and the step of rubbing the polymer film in a given direction by cloth or the like.
Although the liquid crystal orientation film formed by the oblique vapor deposition method is highly advantageous for imparting a given pretilt angle, but because of a vacuum deposition method, it requires a high vacuum of ca. 10.sup.-5 torr and also it is necessary to tilt the substrate, thus the method has a drawback of lacking in mass-producibility.
A liquid crystal orientation film formed by the rubbing method has a drawback of its producibility being affected by dust and static electricity resulting from rubbing and the quality of film being adversely affected.
Hence, a liquid crystal orientation film which can be formed without relying on such conventional methods has been expected.
Recently, a novel type of a liquid crystal orientation film by the use of Langmuir-Blodgett (hereinafter referred to as LB) film which do not require rubbing treatment (Japanese Laid-open Patent Publication No. 209415/1987, Japanese Laid-open Patent Publication No. 23131/1988) are proposed. When the LB film is used as a liquid crystal orientation film, it is difficult to control the pretilt angle of liquid crystal and, depending on the kind of a LB film material used, the liquid crystals are sometimes completely aligned perpendicular or perfectly parallel to the substrate, this resulting in limitation of practicality as a liquid crystal element.
The present invention has been made for solving problems of such conventional arts and is aimed at provision of a liquid crystal orientation film whose liquid crystal pretilt angle is controllable and which is uniform and free from defects.